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Meta Parameters

  • Artikkel

Applies to: Windows | Windows Server

Meta Parameters

This topic contains parameters that are used to control other parameters.

JET_paramConfiguration
129
This parameter exposes multiple sets of default values for the entire set of system parameters. When this parameter is set to a specific configuration, all system parameter values are reset to their default values for that configuration. If the configuration is set for a specific instance then global system parameters will not be reset to their default values.

In addition, the parameter itself can have other effects on the behavior of the database engine.

At this time, there are two supported configurations:

  • Small Configuration (0): The database engine is optimized for memory use.

  • Legacy Configuration (1): The database engine has its traditional defaults.

Small Configuration changes the defaults of the following system parameters to the specified values:

System Parameter

New Default Value

JET_paramMaxSessions

30000

JET_paramMaxOpenTables

2147483647

JET_paramMaxCursors

2147483647

JET_paramMaxVerPages

2147483647

JET_paramMaxTemporaryTables

2147483647

JET_paramLogFileSize

64

JET_paramLogBuffers

1

JET_paramDbExtensionSize

16

JET_paramPageTempDBMin

14

JET_paramCacheSizeMax

16

JET_paramCheckpointDepthMax

65536

JET_paramLRUKHistoryMax

10

JET_paramOutstandingIOMax

16

JET_paramStartFlushThreshold

1

JET_paramStopFlushThreshold

2

JET_paramNoInformationEvent

1

JET_paramCacheSizeMin

16

JET_paramPreferredVerPages

2147483647

JET_paramLogFileCreateAsynch

0

JET_paramGlobalMinVerPages

1

JET_paramPageHintCacheSize

32

JET_paramDisablePerfmon

1

JET_paramEnableFileCache

1

JET_paramEnableViewCache

1

JET_paramVerPageSize

1024

JET_paramEnableAdvanced

0

JET_paramCheckpointIOMax

8

Small Configuration also has several other effects on the database engine, including:

  • All resources managed by system parameters are allocated from the heap as needed

  • Other internal resources used by the database engine are scaled down in size

  • Various maintenance activities are scaled back to avoid background thread activity

Label Value

Default Value:

1 (Legacy)

Type:

Integer

Valid Range:

0 – 1

Scope:

Instance

Set After JetCreateInstance:

Yes

Set after JetInit:

No

Affects Physical Layout:

No

Affects Reliability:

No

Affects Performance:

Yes

Affects Resources:

Yes

Availability:

Starting with Windows Server 2008 and Windows Vista

JET_paramEnableAdvanced
130
This parameter is used to control when the database engine accepts or rejects changes to a subset of the system parameters. This parameter is used in conjunction with JET_paramConfiguration to prevent some system parameters from being set away from the selected configuration's defaults.

The following system parameters will be protected from being set when this parameter is set to False:

  • JET_paramMaxSessionsfon

  • JET_paramMaxOpenTables

  • JET_paramPreferredMaxOpenTables

  • JET_paramMaxCursors

  • JET_paramMaxVerPages

  • JET_paramMaxTemporaryTables

  • JET_paramLogBuffers

  • JET_paramWaitLogFlush

  • JET_paramLogCheckpointPeriod

  • JET_paramLogWaitingUserMax

  • JET_paramDbExtensionSize

  • JET_paramPageTempDBMin

  • JET_paramPageFragment

  • JET_paramBatchIOBufferMax

  • JET_paramCacheSizeMax

  • JET_paramLRUKCorrInterval

  • JET_paramLRUKHistoryMax

  • JET_paramLRUKPolicy

  • JET_paramLRUKTimeout

  • JET_paramLRUKTrxCorrInterval

  • JET_paramOutstandingIOMax

  • JET_paramStartFlushThreshold

  • JET_paramStopFlushThreshold

  • JET_paramCacheSize

  • JET_paramCacheSizeMin

  • JET_paramPreferredVerPages

  • JET_paramBackupChunkSize

  • JET_paramBackupOutstandingReads

  • JET_paramLogFileCreateAsynch

  • JET_paramRecordUpgradeDirtyLevel

  • JET_paramGlobalMinVerPages

  • JET_paramPageHintCacheSize

  • JET_paramVersionStoreTaskQueueMax

  • JET_paramDBAPageAvailMin

  • JET_paramMaxRandomIOSize

  • JET_paramCachedClosedTables

  • JET_paramEnableFileCache

  • JET_paramEnableViewCache

  • JET_paramVerPageSize

  • JET_paramCheckpointIOMax

Label Value

Default Value:

True

Type:

Boolean

Valid Range:

False, True

Scope:

Instance

Set After JetCreateInstance:

Yes

Set after JetInit:

Yes

Affects Physical Layout:

No

Affects Reliability:

No

Affects Performance:

No

Affects Resources:

No

Availability:

Starting with Windows Server 2008 and Windows Vista

Requirements

Requirement Value

Client

Requires Windows Vista.

Server

Requires Windows Server 2008.

Header

Declared in Esent.h.

See Also

JetCreateInstance
JetInit